1. Field of the Invention
This invention relates to the field of semiconductor devices and, more particularly, to a semiconductor device having a light emitting zone and a light detecting zone adaptable for concurrently interfacing with an optical fiber.
Semiconductor devices such as the present invention are useful in communicating between two points over an optical fiber in lieu of conventional cables and electronic transmission. The advantages of such communication include the electrical isolation commonly obtained with optical couplers as well as an immunity to noise picked up and transmitted by conventional electronic cables.
2. Description of the Prior Art
Semiconductor devices having both a light emitting zone and a light detecting zone do exist. However, I am unaware of any device such as the present invention which is capable of directly interfacing a single optical fiber with separate light emitting and light detecting zones. Thus, to the best of my knowledge, the prior art is comprised of devices having only single zones adaptable for interfacing with an optical fiber. In such devices, the zones perform either both light emitting and light detecting functions, or perform only one of these functions. The present invention has significant advantages over such prior art.
An advantage of the present invention over using one device having a light emitting zone and another device having a light detecting zone is that one does not require a fiber optic assembly having a Y branch leading to separate semiconductor devices. In such a fiber optic assembly, three optical fibers are joined at a junction, thus forming a Y branch having three legs. A first leg goes to a light emitting device, a second legs goes to a light detecting device, and a third leg is used for bidirectional data transmission. By eliminating the Y branch through using a single optical fiber to interface with both the light emitting zone and the light detecting zone, the present invention improves optical transmission since there is no Y branch in which optical losses occur.
In addition, the present invention has advantages over a device having a single zone used for both light emitting and light detecting functions. With the present invention, the operating characteristics of both the light emitting zone and the light detecting zone can be optimized for their respective purposes, while a device having a single zone for both light emission and light detection is generally not optimized for both functions. Thus, a single zone device generally performs at least one of its functions less than optimally, especially when normal biasing voltages are applied.
As a further advantage over single zone devices, the present invention provides separate electrical contacts for the emitter zone and the detector zone. As a result, there is no need to multiplex one electrical contact and share it for both light emitting and light detecting as is necessary if a single zone were used for both functions. Thus, the present invention may allow use of more simple circuitry than is possible with single zone devices performing both functions.